1. Field of the Invention
The present invention relates to the field of liquid crystal displaying, and in particular to a side-edge backlight module.
2. The Related Arts
Liquid crystal display (LCD) has a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and is thus widely used. Most of the LCDs that are currently available in the market are backlighting LCDs, which comprise a liquid crystal panel and a backlight module. The operation principle of the liquid crystal panel is that liquid crystal molecules are interposed between two parallel glass substrates and the liquid crystal molecules are controlled to change direction by application of electricity in order to refract light emitting from the backlight module for generating images. Since the liquid crystal panel itself does not emit light, light must be provided by the backlight module in order to normally display images. Thus, the backlight module is one of the key components of an LCD. The backlight module can be classified in two types, namely side-edge backlight module and direct backlight module, according to the position where light gets incident. The direct backlight module arranges a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED), at the back side of the liquid crystal panel to form a planar light source that directly provides lighting to the liquid crystal panel. The side-edge backlight module arranges an LED light bar of a backlight source at an edge of a backplane that is located rearward of one side of the liquid crystal panel. The LED light bar emits light that enters a light guide plate (LGP) through a light incident face of the light guide plate and is projected out through a light exit face of the light guide plate, after being reflected and diffused, to thereby transmit through an optic film assembly and form a planar light source for the liquid crystal panel.
Referring to FIG. 1, the side-edge backlight module comprises: a backplane 100, a reflector plate 200 arranged inside the backplane 100, a light guide plate 300 arranged on the reflector plate 200, a backlight source 400 arranged inside the backplane 100, and a heat dissipation board 500 arranged between the backlight source 400 and the backplane 100. The backplane 100 comprises a bottom plate 102 and a side plate 104 connected to the bottom plate 102. The backlight source 400 is mounted through thermal paste (not shown) to the heat dissipation board 500. The heat dissipation board 500 is usually an aluminum extrusion, which is fixed by screws to the bottom plate 102 of the backplane 100. Heat emitting from the backlight source 400 is conducted through the heat dissipation board 500 to the bottom plate 102 of the backplane 100 and is subjected to heat exchange with the surrounding atmosphere through the backplane 100. However, since the thermal paste is of a power thermal conductivity, the heat dissipation performance of the backlight module is poor, thereby affecting the quality of the backlight module.
Further, referring to FIG. 2, to support the light guide plate 300, a raised platform 502 is formed on the heat dissipation board 500′. The reflector plate 200 is supported on the raised platform 502 and the light guide plate 300 is positioned on the reflector plate 200. However, forming the raised platform 502 increases the consumption of material for the aluminum extrusion. This increases the manufacturing cost and increases the weight of the backlight module, making it adverse to weight reduction of the backlight module.
Referring to FIG. 3, to handle the above discussed issues, technicians of this field adopts a plastic strip 600 attached to the raised platform 502′ in order to take place some of the height in order to reduce the amount of material used for the aluminum extrusion for reducing the weight of the backlight module. However, the plastic strip 600 requires preparation of plastic and fixation and this increase manufacturing process thereby increasing the manufacturing cost.